Mechanical pencil



' March 23, 1943- H. M. FARRINGTON MECHANICAL PENCIL Filed Aug. 18, 1941 Patented Mar. 23, 1943 MECIIANICAL PENCIL Hastings Macleod Farrington, London, England Application August 18, 1941, Serial No. 407,360 In Great BritainAugust 17, 1940 4 Claims.

(Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G. 5)

This invention aims to provide an efiicient mechanical pencil of simple and inexpensive construction, in which a lead carrier is slidably disposed within a body orcasing of the pencil, a part of said lead carrier, or a member associated therewith, extending outwardly and projecting through a longitudinal slot formed in the wall of the casing, and by the aid of which leadcarrier projection the lead may be propelled beyond the pointed end of the pencil into position for writing, or retracted into the casing when not required for use; a characteristic feature of my pencil being that the lead carrier and so the lead becomes securely locked merely in the sliding adjustment of the latter into writing position, (or, alternatively, to a-position in which the lead becomes housed in the casing) so that there is an absence of any rearward movement orinadvertent slippage of the lead when writing pressure is imposed on the point thereof.

A mechanical pencil, according to one form of embodiment under my invention, includes a body or casing provided with a longitudinal slot, a lead-carrier slidably disposed'within said casing, said carrier having a forward portion adapted to hold a lead or other writing medium in rod or stick form, and an after part formed as or fitted with a resilient piece or extension (hereinafter, for convenience of reference designated retaining member) such as an appropriately bent strip of springy metalwhich extends rearwardly and then outwardly, preferably in the form of an obtuse angle, so that its free end normally (i. e. when the lead-carrier is not being projected or retracted in the casing by the user) abuts against the inner wall of the casing near the marginal edges borderingsaid casing slot .to lock the lead-carrier and so the lead against rearward displacement; and there being attached to or formed on and extending from the free end portion of the retaining member a piece of lesser width than that of the latter, which projects through said casing slot so as to slide therein when pressed inwardly by the finger or thumb of the user of the pencil to free the retaining member of the lead-carrier from looking engagement with the casing and permit the pencil lead to be slid into position for writing, or retracted into the casing as may be desired.

In a modified pencil construction, under my invention, instead of the spring retaining member of a lead-carrier engaging directly with the pencil casing itself, it is adapted to co-operate with a lead-carrier guide tube, or its equivalent,

disposed within the casing and so slotted or formed as to provide a cross-section greater than a semi-circle, or a slot less in width than the inside diameter or width of the tube. The slot of said lead-carrier guide tube is, of course, arranged in register or alignment with the slot of the pencil casing, and the finger piece operates through both slots.

I will further describe my invention with the aid of the accompanying sheet of explanatory drawings which illustrate, by way of examples only, two modes of carrying the same into efiect.

In said drawing:

Figs. 1 to 5, inclusive, represent one mode of embodiment, and Figs. 6 to 7 a modified construction.

In the several views, in which like characters of reference denote like or equivalent parts wherever they occur,

Fig. 1 is an elevation,

Fig. 2 a longitudinal section,

Figs. 3 and 4 elevations, taken at right angles to each other, of the lead-carrier unit removed from the pencil, and

Fig; 5 a cross-section taken as on the line 5-5 of Fig. 2.

In the views (Figs. 6 and 7) illustrating the modified pencil construction, Fig. 6 is a longitudinal section (the pencil point being omitted) and Fig. '7 is a cross-section taken as on the line 11 of Fig. 6.

Referring first more particularly to Figs. 1 to 5, inclusive, I denotes a pencil body or casing of any suitable material such as a synthetic resin composition or like moulded product, and wherein a longitudinal slot 2 is formed: the forward end of the casing itself may be tapered to pro-,

vide a point section l but in the example illustrated the point section is of metal in screw engagement with the casing I.

Within the passage or bore 3 of casing I there is slidably disposed a lead-carrier made of sheet metal having a forward end 4 bent into tubular configuration for the reception of an end of a writing lead 5, and a rear or after part formed as a resilient extension strip '4 with a rear mounting portion 4 which functions as a retaining member of the lead-carrier.

From the lead-carrier tube 4 the retaining member 4 extends rearwardly in bore 3 of casing l and then outwardly, making an obtuse angle as shown between its forward leg or portion and its rear mounting leg or portion M.

The free end of mounting portion l of retaining member 4 is of greater width than that of slot 2 of casing l and extends transversely of the slot, its edge portion 4 being spring-pressed against the underside of the casing wall adjacent the edges or margins bordering said slot, and secured to said free end of retaining member 4* is a finger piece 4 which extends through and projects from the slot. Said finger piece i is secured, as by the rivet 4 in the middle of the width of the retaining member 4 50 that its edge 4 extends equally beyond either side of casing slot 2.

The rear end of said pencil casing l is closed by a cap 6 which, when removed, as when it is required to fit a new lead, enables the lead-carrier assembly i 4, a, i to be withdrawn as a unit from the casing bore 3.

To longitudinally adjust pencil 5, the external finger piece i is pressed inwardly against the inherent spring resistance of the lead-carrier retaining member 4 which tends to pivot or hinge about the point a: so as to cause the contacting portions of its'edge- 5 to recede from their frictional contact or engagement with the inner Wall of easing I i. e. at the points 1, I (Fig. 5) near casing slot 2, thus permitting said lead-carrier assembly to be freely slid, by the finger piece 4 forwardly until the desired amount of lead 5 is projected from the point section W, or, alternatively, rearwardly to shield the pencil point, as may be desired.

Vlhen the lead 5 has been advanced to the writing position desired by the user of the pencil, pressure on finger piece 4 is released to permit the edge 4 of the retaining member to resume spring engagement with the Wall (points 'i) bordering the casing slot 2 and thereby lock the leadcarrier, and so the lead, against accidental retractional displacement when the pencil is being used for writing, due to writing pressure upon the pencil point, as under such pressure the consequential rearward thrust on the retaining member tends to cause its free extremity 4 more firmly to bite into that part of the casing inner wall where said extremity then coincides.

It will thus be seen that adjustment of the lead is effected without the aid of any ratchet device and does not necessitate rotary movement of any part of the mechanism, while its movement can only be effected when the finger piece 4 is intentionally displaced inwardly by the user to release the retaining member from its normal frictional contact with the inner wall of the pencil casing.

Referring now to the modification illustrated in Figs. 6 and 7 of the drawing, a lead-carrier assembly t 4*, 4 4 (in this construction the rear resilient component 4* is not bent into angular configuration as in the previous example but it may be so bent) isslidably disposed within a metal guide tube 8 disposed within bore 3 of pencil casing I, and which tube 8 is so slotted or formed throughout its length as to provide a cross-section greater than a semi-circle-i. e. slot 9 is less in width than the inside diameter of guide tube 8. Said tube is secured to a cap 6 which also closes the rear end of the casing l, and the tube slot 9 is in register or alignment with casing slot 2. The free end 4 of the retaining member is of spear-like or tapering conformation and (instead of contacting with the casing l itself as in the previous example) frictionally engages with the edges of the tube slot 9 where its width is greater than that of the slot, firm engagement of said retaining member being normally efiected by means of its inherent springiness, and in order to improve such frictional contact the edges of said free end of the retaining member may be sharpened so that they tend to bite into the edges of the tube slot.

To propel lead 5, finger piece 4 which projects through longitudinal slot 2 of the pencil casing l is pressed inwardly against the spring resistance of the lead-carrier retaining member 4* which is thereby also depressed so that its free extremity 4 moves out of frictional engagement with the edges of the tube slot 9 to permit the lead carrier assembly unit to be freely slid forward until the lead is projected from the point section of the casing.

When the lead is advanced to appropriate writing position, the finger piece 4 is released and automatically returns to its normal position to allow the spring retaining member 4* to return so that its tapering end 4 resumes engagement with the wall edges of the tube slot 9 and thereby lock the lead carrier against rearward displacement as the pencil is being used, pressure upon the pencil lead tending to more firmly cause the free end 4 of the retaining member to bite into the edges of the tube slot 9, as in the previous example.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a mechanical pencil, a hollow body casing having a longitudinal slot formed in the wall thereof, an integrally formed carrier member adapted to be received within the bore of said casing and having a forward portion of tubular configuration adapted to receive a writing lead, and further having a rear portion formed as a resilient strip and being bent at a point intermediate its length to form a forward leg and a back leg which make an obtuse angle between them, said angle and the lengths of said legs being of such values that when said carrier member is positioned within the bore of said casing, the common point of said legs impinges on the wall of the bore of said casing and the free end of said back leg is resiliently lockingly impinged on the opposite side of the inner wall of the bore of said casing, whereby application of upward pressure from said lead on said carrier member during writing intensifies the grip of the locking impingement of said free end on said wall.

2. In a mechanical pencil, a hollow body casing having a longitudinal slot formed in the wall thereof, an integrally formed carrier member adapted to be received within the bore of said casing and having a forward portion of tubular configuration adapted to receive a writing lead, and further having a rear portion formed as a resilient strip and being bent at a point intermediate its length to form a forward leg and a back leg which make an obtuse angle between them, the back free end of said back leg being wider than said slot, and a finger piece adapted to pass through said slot and being attached to the back end of said back leg, said angle and the lengths of said legs being of such values that when said carrier member is positioned Within the bore of said casing with said finger piece passing through said slot, the common point of said legs impinges on the wall of the bore of said casing and the free end of said back leg is normally lockingly resiliently impinged on the opposite side of the inner wall of the bore of said casing adjacent said slot, whereby pressure on said finger piece will release said free end from locking impingement on said wall, and said carrier member may be longitudinally adjusted within said casing.

3. In a mechanical pencil, a hollow body casing having a longitudinal slot formed in the wall thereof, an integrally formed carrier member adapted to be received Within the bore of said casing and having a forward portion of tubular configuration adapted to receive a writing lead, and further having a rear portion formed as a resilient strip and being bent at a point intermediate its length to form a forward leg and a back leg which make an obtuse angle between them, the back free end of said back leg being wider than said slot and being provided with a spear terminal, and a finger piece adapted to pass through said slot and being attached to said back leg, said angle and the lengths of said legs being of such values that when said carrier member is positioned within the bore of said casing with said finger piece passing through said slot, the common point of said legs impinges on the wall of the bore of said casing and the spear terminal of the free end of said back leg is normally lookingly resilient impinged on the edges of said slot, whereby pressure on said finger piece will release said free end from looking impingement on said casing, and said carrier member may be longitudinally adjusted within said casing.

' 4. A pencil according to claim 1, the wall of the bore of said casing being smooth and without rack element structure. 7

HASTINGS MACLEOD FARRINGTON. 

